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/*

 * Copyright (c) 2006 Ondrej Palkovsky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup genericipc

 * @{

 */

/** @file

 */

#include <arch.h>

#include <proc/task.h>

#include <proc/thread.h>

#include <errno.h>

#include <memstr.h>

#include <debug.h>

#include <ipc/ipc.h>

#include <ipc/sysipc.h>

#include <ipc/irq.h>

#include <ipc/ipcrsc.h>

#include <ipc/kbox.h>

#include <udebug/udebug_ipc.h>

#include <arch/interrupt.h>

#include <syscall/copy.h>

#include <security/cap.h>

#include <mm/as.h>

#include <print.h>

/**

 * Maximum buffer size allowed for IPC_M_DATA_WRITE and IPC_M_DATA_READ

 * requests.

 */

#define DATA_XFER_LIMIT		(64 * 1024)

#define GET_CHECK_PHONE(phone, phoneid, err) \

{ \

	if (phoneid > IPC_MAX_PHONES) { \

		err; \

	} \

	phone = &TASK->phones[phoneid]; \

}

#define STRUCT_TO_USPACE(dst, src)	copy_to_uspace(dst, src, sizeof(*(src)))

/** Decide if the method is a system method.

 *

 * @param method	Method to be decided.

 *

 * @return		Return 1 if the method is a system method.

 *			Otherwise return 0.

 */

static inline int method_is_system(unative_t method)

{

	if (method <= IPC_M_LAST_SYSTEM)

		return 1;

	return 0;

}

/** Decide if the message with this method is forwardable.

 *

 * - some system messages may be forwarded, for some of them

 *   it is useless

 *

 * @param method	Method to be decided.

 *

 * @return		Return 1 if the method is forwardable.

 *			Otherwise return 0.

 */

static inline int method_is_forwardable(unative_t method)

{

	switch (method) {

	case IPC_M_CONNECTION_CLONE:

	case IPC_M_CONNECT_ME:

	case IPC_M_PHONE_HUNGUP:

		/* This message is meant only for the original recipient. */

		return 0;

	default:

		return 1;

	}

}

/** Decide if the message with this method is immutable on forward.

 *

 * - some system messages may be forwarded but their content cannot be altered

 *

 * @param method	Method to be decided.

 *

 * @return		Return 1 if the method is immutable on forward.

 *			Otherwise return 0.

 */

static inline int method_is_immutable(unative_t method)

{

	switch (method) {

	case IPC_M_SHARE_OUT:

	case IPC_M_SHARE_IN:

	case IPC_M_DATA_WRITE:

	case IPC_M_DATA_READ:

		return 1;

		break;

	default:

		return 0;

	}

}

/***********************************************************************

 * Functions that preprocess answer before sending it to the recepient.

 ***********************************************************************/

/** Decide if the caller (e.g. ipc_answer()) should save the old call contents

 * for answer_preprocess().

 *

 * @param call		Call structure to be decided.

 *

 * @return		Return 1 if the old call contents should be saved.

 *			Return 0 otherwise.

 */

static inline int answer_need_old(call_t *call)

{

	switch (IPC_GET_METHOD(call->data)) {

	case IPC_M_CONNECTION_CLONE:

	case IPC_M_CONNECT_ME:

	case IPC_M_CONNECT_TO_ME:

	case IPC_M_CONNECT_ME_TO:

	case IPC_M_SHARE_OUT:

	case IPC_M_SHARE_IN:

	case IPC_M_DATA_WRITE:

	case IPC_M_DATA_READ:

		return 1;

	default:

		return 0;

	}

}

/** Interpret process answer as control information.

 *

 * This function is called directly after sys_ipc_answer().

 *

 * @param answer	Call structure with the answer.

 * @param olddata	Saved data of the request.

 *

 * @return		Return 0 on success or an error code. 

 */

static inline int answer_preprocess(call_t *answer, ipc_data_t *olddata)

{

	int phoneid;

	if ((native_t) IPC_GET_RETVAL(answer->data) == EHANGUP) {

		/* In case of forward, hangup the forwared phone,

		 * not the originator

		 */

		mutex_lock(&answer->data.phone->lock);

		spinlock_lock(&TASK->answerbox.lock);

		if (answer->data.phone->state == IPC_PHONE_CONNECTED) {

			list_remove(&answer->data.phone->link);

			answer->data.phone->state = IPC_PHONE_SLAMMED;

		}

		spinlock_unlock(&TASK->answerbox.lock);

		mutex_unlock(&answer->data.phone->lock);

	}

	if (!olddata)

		return 0;

	if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECTION_CLONE) {

		phoneid = IPC_GET_ARG1(*olddata);

		phone_t *phone = &TASK->phones[phoneid]; 

		if (IPC_GET_RETVAL(answer->data) != EOK) {

			/*

			 * The recipient of the cloned phone rejected the offer.

			 * In this case, the connection was established at the

			 * request time and therefore we need to slam the phone.

			 * We don't merely hangup as that would result in

			 * sending IPC_M_HUNGUP to the third party on the

			 * other side of the cloned phone.

			 */

			mutex_lock(&phone->lock);

			if (phone->state == IPC_PHONE_CONNECTED) {

				spinlock_lock(&phone->callee->lock);

				list_remove(&phone->link);

				phone->state = IPC_PHONE_SLAMMED;

				spinlock_unlock(&phone->callee->lock);

			}

			mutex_unlock(&phone->lock);

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECT_ME) {

		phone_t *phone = (phone_t *)IPC_GET_ARG5(*olddata);

		if (IPC_GET_RETVAL(answer->data) != EOK) {

			/*

			 * The other party on the cloned phoned rejected our

			 * request for connection on the protocol level.

			 * We need to break the connection without sending

			 * IPC_M_HUNGUP back.

			 */

			mutex_lock(&phone->lock);

			if (phone->state == IPC_PHONE_CONNECTED) {

				spinlock_lock(&phone->callee->lock);

				list_remove(&phone->link);

				phone->state = IPC_PHONE_SLAMMED;

				spinlock_unlock(&phone->callee->lock);

			}

			mutex_unlock(&phone->lock);

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECT_TO_ME) {

		phoneid = IPC_GET_ARG5(*olddata);

		if (IPC_GET_RETVAL(answer->data) != EOK) {

			/* The connection was not accepted */

			phone_dealloc(phoneid);

		} else {

			/* The connection was accepted */

			phone_connect(phoneid, &answer->sender->answerbox);

			/* Set 'phone hash' as arg5 of response */

			IPC_SET_ARG5(answer->data,

			    (unative_t) &TASK->phones[phoneid]);

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_CONNECT_ME_TO) {

		/* If the users accepted call, connect */

		if (IPC_GET_RETVAL(answer->data) == EOK) {

			ipc_phone_connect((phone_t *) IPC_GET_ARG5(*olddata),

			    &TASK->answerbox);

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_SHARE_OUT) {

		if (!IPC_GET_RETVAL(answer->data)) {

			/* Accepted, handle as_area receipt */

			ipl_t ipl;

			int rc;

			as_t *as;

			ipl = interrupts_disable();

			spinlock_lock(&answer->sender->lock);

			as = answer->sender->as;

			spinlock_unlock(&answer->sender->lock);

			interrupts_restore(ipl);

			rc = as_area_share(as, IPC_GET_ARG1(*olddata),

			    IPC_GET_ARG2(*olddata), AS,

			    IPC_GET_ARG1(answer->data), IPC_GET_ARG3(*olddata));

			IPC_SET_RETVAL(answer->data, rc);

			return rc;

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_SHARE_IN) {

		if (!IPC_GET_RETVAL(answer->data)) { 

			ipl_t ipl;

			as_t *as;

			int rc;

			ipl = interrupts_disable();

			spinlock_lock(&answer->sender->lock);

			as = answer->sender->as;

			spinlock_unlock(&answer->sender->lock);

			interrupts_restore(ipl);

			rc = as_area_share(AS, IPC_GET_ARG1(answer->data),

			    IPC_GET_ARG2(*olddata), as, IPC_GET_ARG1(*olddata),

			    IPC_GET_ARG2(answer->data));

			IPC_SET_RETVAL(answer->data, rc);

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_DATA_READ) {

		ASSERT(!answer->buffer);

		if (!IPC_GET_RETVAL(answer->data)) {

			/* The recipient agreed to send data. */

			uintptr_t src = IPC_GET_ARG1(answer->data);

			uintptr_t dst = IPC_GET_ARG1(*olddata);

			size_t max_size = IPC_GET_ARG2(*olddata);

			size_t size = IPC_GET_ARG2(answer->data);

			if (size && size <= max_size) {

				/*

				 * Copy the destination VA so that this piece of

				 * information is not lost.

				 */

				IPC_SET_ARG1(answer->data, dst);

				answer->buffer = malloc(size, 0);

				int rc = copy_from_uspace(answer->buffer,

				    (void *) src, size);

				if (rc) {

					IPC_SET_RETVAL(answer->data, rc);

					free(answer->buffer);

					answer->buffer = NULL;

				}

			} else if (!size) {

				IPC_SET_RETVAL(answer->data, EOK);

			} else {

				IPC_SET_RETVAL(answer->data, ELIMIT);

			}

		}

	} else if (IPC_GET_METHOD(*olddata) == IPC_M_DATA_WRITE) {

		ASSERT(answer->buffer);

		if (!IPC_GET_RETVAL(answer->data)) {

			/* The recipient agreed to receive data. */

			int rc;

			uintptr_t dst;

			size_t size;

			size_t max_size;

			dst = (uintptr_t)IPC_GET_ARG1(answer->data);

			size = (size_t)IPC_GET_ARG2(answer->data);

			max_size = (size_t)IPC_GET_ARG2(*olddata);

			if (size <= max_size) {

				rc = copy_to_uspace((void *) dst,

				    answer->buffer, size);

				if (rc)

					IPC_SET_RETVAL(answer->data, rc);

			} else {

				IPC_SET_RETVAL(answer->data, ELIMIT);

			}

		}

		free(answer->buffer);

		answer->buffer = NULL;

	}

	return 0;

}

static void phones_lock(phone_t *p1, phone_t *p2)

{

	if (p1 < p2) {

		mutex_lock(&p1->lock);

		mutex_lock(&p2->lock);

	} else if (p1 > p2) {

		mutex_lock(&p2->lock);

		mutex_lock(&p1->lock);

	} else {

		mutex_lock(&p1->lock);

	}

}

static void phones_unlock(phone_t *p1, phone_t *p2)

{

	mutex_unlock(&p1->lock);

	if (p1 != p2)

		mutex_unlock(&p2->lock);

}

/** Called before the request is sent.

 *

 * @param call		Call structure with the request.

 * @param phone		Phone that the call will be sent through.

 *

 * @return 		Return 0 on success, ELIMIT or EPERM on error.

 */

static int request_preprocess(call_t *call, phone_t *phone)

{

	int newphid;

	size_t size;

	uintptr_t src;

	int rc;

	switch (IPC_GET_METHOD(call->data)) {

	case IPC_M_CONNECTION_CLONE: {

		phone_t *cloned_phone;

		GET_CHECK_PHONE(cloned_phone, IPC_GET_ARG1(call->data),

		    return ENOENT);

		phones_lock(cloned_phone, phone);

		if ((cloned_phone->state != IPC_PHONE_CONNECTED) ||

		    phone->state != IPC_PHONE_CONNECTED) {

			phones_unlock(cloned_phone, phone);

			return EINVAL;

		}

		/*

		 * We can be pretty sure now that both tasks exist and we are

		 * connected to them. As we continue to hold the phone locks,

		 * we are effectively preventing them from finishing their

		 * potential cleanup.

		 */

		newphid = phone_alloc(phone->callee->task);

		if (newphid < 0) {

			phones_unlock(cloned_phone, phone);

			return ELIMIT;

		}

		ipc_phone_connect(&phone->callee->task->phones[newphid],

		    cloned_phone->callee);

		phones_unlock(cloned_phone, phone);

		/* Set the new phone for the callee. */

		IPC_SET_ARG1(call->data, newphid);

		break;

	}

	case IPC_M_CONNECT_ME:

		IPC_SET_ARG5(call->data, (unative_t) phone);

		break;

	case IPC_M_CONNECT_ME_TO:

		newphid = phone_alloc(TASK);

		if (newphid < 0)

			return ELIMIT;

		/* Set arg5 for server */

		IPC_SET_ARG5(call->data, (unative_t) &TASK->phones[newphid]);

		call->flags |= IPC_CALL_CONN_ME_TO;

		call->priv = newphid;

		break;

	case IPC_M_SHARE_OUT:

		size = as_area_get_size(IPC_GET_ARG1(call->data));

		if (!size)

			return EPERM;

		IPC_SET_ARG2(call->data, size);

		break;

	case IPC_M_DATA_READ:

		size = IPC_GET_ARG2(call->data);

		if ((size <= 0 || (size > DATA_XFER_LIMIT)))

			return ELIMIT;

		break;

	case IPC_M_DATA_WRITE:

		src = IPC_GET_ARG1(call->data);

		size = IPC_GET_ARG2(call->data);

		if (size > DATA_XFER_LIMIT)

			return ELIMIT;

		call->buffer = (uint8_t *) malloc(size, 0);

		rc = copy_from_uspace(call->buffer, (void *) src, size);

		if (rc != 0) {

			free(call->buffer);

			return rc;

		}

		break;

#ifdef CONFIG_UDEBUG

	case IPC_M_DEBUG_ALL:

		return udebug_request_preprocess(call, phone);

#endif

	default:

		break;

	}

	return 0;

}

/*******************************************************************************

 * Functions called to process received call/answer before passing it to uspace.

 *******************************************************************************/

/** Do basic kernel processing of received call answer.

 *

 * @param call		Call structure with the answer.

 */

static void process_answer(call_t *call)

{

	if (((native_t) IPC_GET_RETVAL(call->data) == EHANGUP) &&

	    (call->flags & IPC_CALL_FORWARDED))

		IPC_SET_RETVAL(call->data, EFORWARD);

	if (call->flags & IPC_CALL_CONN_ME_TO) {

		if (IPC_GET_RETVAL(call->data))

			phone_dealloc(call->priv);

		else

			IPC_SET_ARG5(call->data, call->priv);

	}

	if (call->buffer) {

		/* This must be an affirmative answer to IPC_M_DATA_READ. */

		/* or IPC_M_DEBUG_ALL/UDEBUG_M_MEM_READ... */

		uintptr_t dst = IPC_GET_ARG1(call->data);

		size_t size = IPC_GET_ARG2(call->data);

		int rc = copy_to_uspace((void *) dst, call->buffer, size);

		if (rc)

			IPC_SET_RETVAL(call->data, rc);

		free(call->buffer);

		call->buffer = NULL;

	}

}

/** Do basic kernel processing of received call request.

 *

 * @param box		Destination answerbox structure.

 * @param call		Call structure with the request.

 *

 * @return 		Return 0 if the call should be passed to userspace.

 *			Return -1 if the call should be ignored.

 */

static int process_request(answerbox_t *box, call_t *call)

{

	int phoneid;

	if (IPC_GET_METHOD(call->data) == IPC_M_CONNECT_TO_ME) {

		phoneid = phone_alloc(TASK);

		if (phoneid < 0) { /* Failed to allocate phone */

			IPC_SET_RETVAL(call->data, ELIMIT);

			ipc_answer(box, call);

			return -1;

		}

		IPC_SET_ARG5(call->data, phoneid);

	}

	switch (IPC_GET_METHOD(call->data)) {

	case IPC_M_DEBUG_ALL:

		return -1;

	default:

		break;

	}

	return 0;

}

/** Make a fast call over IPC, wait for reply and return to user.

 *

 * This function can handle only three arguments of payload, but is faster than

 * the generic function (i.e. sys_ipc_call_sync_slow()).

 *

 * @param phoneid	Phone handle for the call.

 * @param method	Method of the call.

 * @param arg1		Service-defined payload argument.

 * @param arg2		Service-defined payload argument.

 * @param arg3		Service-defined payload argument.

 * @param data		Address of userspace structure where the reply call will

 *			be stored.

 *

 * @return		Returns 0 on success.

 *			Return ENOENT if there is no such phone handle.

 */

unative_t sys_ipc_call_sync_fast(unative_t phoneid, unative_t method,

    unative_t arg1, unative_t arg2, unative_t arg3, ipc_data_t *data)

{

	call_t call;

	phone_t *phone;

	int res;

	int rc;

	GET_CHECK_PHONE(phone, phoneid, return ENOENT);

	ipc_call_static_init(&call);

	IPC_SET_METHOD(call.data, method);

	IPC_SET_ARG1(call.data, arg1);

	IPC_SET_ARG2(call.data, arg2);

	IPC_SET_ARG3(call.data, arg3);

	/*

	 * To achieve deterministic behavior, zero out arguments that are beyond

	 * the limits of the fast version.

	 */

	IPC_SET_ARG4(call.data, 0);

	IPC_SET_ARG5(call.data, 0);

	if (!(res = request_preprocess(&call, phone))) {

#ifdef CONFIG_UDEBUG

		udebug_stoppable_begin();

#endif

		rc = ipc_call_sync(phone, &call);

#ifdef CONFIG_UDEBUG

		udebug_stoppable_end();

#endif

		if (rc != EOK)

			return rc;

		process_answer(&call);

	} else {

		IPC_SET_RETVAL(call.data, res);

	}

	rc = STRUCT_TO_USPACE(&data->args, &call.data.args);

	if (rc != 0)

		return rc;

	return 0;

}

/** Make a synchronous IPC call allowing to transmit the entire payload.

 *

 * @param phoneid	Phone handle for the call.

 * @param question	Userspace address of call data with the request.

 * @param reply		Userspace address of call data where to store the

 *			answer.

 *

 * @return		Zero on success or an error code.

 */

unative_t sys_ipc_call_sync_slow(unative_t phoneid, ipc_data_t *question,

    ipc_data_t *reply)

{

	call_t call;

	phone_t *phone;

	int res;

	int rc;

	ipc_call_static_init(&call);

	rc = copy_from_uspace(&call.data.args, &question->args,

	    sizeof(call.data.args));

	if (rc != 0)

		return (unative_t) rc;

	GET_CHECK_PHONE(phone, phoneid, return ENOENT);

	if (!(res = request_preprocess(&call, phone))) {

#ifdef CONFIG_UDEBUG

		udebug_stoppable_begin();

#endif

		rc = ipc_call_sync(phone, &call);

#ifdef CONFIG_UDEBUG

		udebug_stoppable_end();

#endif

		if (rc != EOK)

			return rc;

		process_answer(&call);

	} else 

		IPC_SET_RETVAL(call.data, res);

	rc = STRUCT_TO_USPACE(&reply->args, &call.data.args);

	if (rc != 0)

		return rc;

	return 0;

}

/** Check that the task did not exceed the allowed limit of asynchronous calls.

 *

 * @return 		Return 0 if limit not reached or -1 if limit exceeded.

 */

static int check_call_limit(void)

{

	if (atomic_preinc(&TASK->active_calls) > IPC_MAX_ASYNC_CALLS) {

		atomic_dec(&TASK->active_calls);

		return -1;

	}

	return 0;

}

/** Make a fast asynchronous call over IPC.

 *

 * This function can only handle four arguments of payload, but is faster than

 * the generic function sys_ipc_call_async_slow().

 *

 * @param phoneid	Phone handle for the call.

 * @param method	Method of the call.

 * @param arg1		Service-defined payload argument.

 * @param arg2		Service-defined payload argument.

 * @param arg3		Service-defined payload argument.

 * @param arg4		Service-defined payload argument.

 *

 * @return 		Return call hash on success.

 *			Return IPC_CALLRET_FATAL in case of a fatal error and 

 *			IPC_CALLRET_TEMPORARY if there are too many pending

 *			asynchronous requests; answers should be handled first.

 */

unative_t sys_ipc_call_async_fast(unative_t phoneid, unative_t method,

    unative_t arg1, unative_t arg2, unative_t arg3, unative_t arg4)

{

	call_t *call;

	phone_t *phone;

	int res;

	if (check_call_limit())

		return IPC_CALLRET_TEMPORARY;

	GET_CHECK_PHONE(phone, phoneid, return IPC_CALLRET_FATAL);

	call = ipc_call_alloc(0);

	IPC_SET_METHOD(call->data, method);

	IPC_SET_ARG1(call->data, arg1);

	IPC_SET_ARG2(call->data, arg2);

	IPC_SET_ARG3(call->data, arg3);

	IPC_SET_ARG4(call->data, arg4);

	/*

	 * To achieve deterministic behavior, zero out arguments that are beyond

	 * the limits of the fast version.

	 */

	IPC_SET_ARG5(call->data, 0);

	if (!(res = request_preprocess(call, phone)))

		ipc_call(phone, call);

	else

		ipc_backsend_err(phone, call, res);

	return (unative_t) call;

}

/** Make an asynchronous IPC call allowing to transmit the entire payload.

 *

 * @param phoneid	Phone handle for the call.

 * @param data		Userspace address of call data with the request.

 *

 * @return		See sys_ipc_call_async_fast(). 

 */

unative_t sys_ipc_call_async_slow(unative_t phoneid, ipc_data_t *data)

{

	call_t *call;

	phone_t *phone;

	int res;

	int rc;

	if (check_call_limit())

		return IPC_CALLRET_TEMPORARY;

	GET_CHECK_PHONE(phone, phoneid, return IPC_CALLRET_FATAL);

	call = ipc_call_alloc(0);

	rc = copy_from_uspace(&call->data.args, &data->args,

	    sizeof(call->data.args));

	if (rc != 0) {

		ipc_call_free(call);

		return (unative_t) rc;

	}

	if (!(res = request_preprocess(call, phone)))

		ipc_call(phone, call);

	else

		ipc_backsend_err(phone, call, res);

	return (unative_t) call;

}

/** Forward a received call to another destination - common code for both the

 * fast and the slow version.

 *

 * @param callid	Hash of the call to forward.

 * @param phoneid	Phone handle to use for forwarding.

 * @param method	New method to use for the forwarded call.

 * @param arg1		New value of the first argument for the forwarded call.

 * @param arg2		New value of the second argument for the forwarded call.

 * @param arg3		New value of the third argument for the forwarded call.

 * @param arg4		New value of the fourth argument for the forwarded call.

 * @param arg5		New value of the fifth argument for the forwarded call.

 * @param mode		Flags that specify mode of the forward operation.

 * @param slow		If true, arg3, arg4 and arg5 are considered. Otherwise

 *			the function considers only the fast version arguments:

 *			i.e. arg1 and arg2.

 *

 * @return		Return 0 on succes, otherwise return an error code.

 *

 * Warning:	Make sure that ARG5 is not rewritten for certain system IPC

 */

static unative_t sys_ipc_forward_common(unative_t callid, unative_t phoneid,

    unative_t method, unative_t arg1, unative_t arg2, unative_t arg3,

    unative_t arg4, unative_t arg5, int mode, bool slow)

{

	call_t *call;

	phone_t *phone;

	call = get_call(callid);

	if (!call)

		return ENOENT;

	call->flags |= IPC_CALL_FORWARDED;

	GET_CHECK_PHONE(phone, phoneid, { 

		IPC_SET_RETVAL(call->data, EFORWARD);

		ipc_answer(&TASK->answerbox, call);

		return ENOENT;

	});

	if (!method_is_forwardable(IPC_GET_METHOD(call->data))) {

		IPC_SET_RETVAL(call->data, EFORWARD);

		ipc_answer(&TASK->answerbox, call);

		return EPERM;

	}

	/*

	 * Userspace is not allowed to change method of system methods on

	 * forward, allow changing ARG1, ARG2, ARG3 and ARG4 by means of method,

	 * arg1, arg2 and arg3.

	 * If the method is immutable, don't change anything.

	 */

	if (!method_is_immutable(IPC_GET_METHOD(call->data))) {

		if (method_is_system(IPC_GET_METHOD(call->data))) {

			if (IPC_GET_METHOD(call->data) == IPC_M_CONNECT_TO_ME)

				phone_dealloc(IPC_GET_ARG5(call->data));

			IPC_SET_ARG1(call->data, method);

			IPC_SET_ARG2(call->data, arg1);

			IPC_SET_ARG3(call->data, arg2);

			if (slow) {

				IPC_SET_ARG4(call->data, arg3);

				/*

				 * For system methods we deliberately don't

				 * overwrite ARG5.

				 */

			}

		} else {

			IPC_SET_METHOD(call->data, method);

			IPC_SET_ARG1(call->data, arg1);

			IPC_SET_ARG2(call->data, arg2);

			if (slow) {

				IPC_SET_ARG3(call->data, arg3);

				IPC_SET_ARG4(call->data, arg4);

				IPC_SET_ARG5(call->data, arg5);

			}

		}

	}

	return ipc_forward(call, phone, &TASK->answerbox, mode);

}

/** Forward a received call to another destination - fast version.

 *

 * @param callid	Hash of the call to forward.

 * @param phoneid	Phone handle to use for forwarding.

 * @param method	New method to use for the forwarded call.

 * @param arg1		New value of the first argument for the forwarded call.

 * @param arg2		New value of the second argument for the forwarded call.

 * @param mode		Flags that specify mode of the forward operation.

 *

 * @return		Return 0 on succes, otherwise return an error code.

 *

 * In case the original method is a system method, ARG1, ARG2 and ARG3 are

 * overwritten in the forwarded message with the new method and the new

 * arg1 and arg2, respectively. Otherwise the METHOD, ARG1 and ARG2 are

 * rewritten with the new method, arg1 and arg2, respectively. Also note there

 * is a set of immutable methods, for which the new method and arguments are not

 * set and these values are ignored.

 */

unative_t sys_ipc_forward_fast(unative_t callid, unative_t phoneid,

    unative_t method, unative_t arg1, unative_t arg2, int mode)

{

	return sys_ipc_forward_common(callid, phoneid, method, arg1, arg2, 0, 0,

	    0, mode, false); 

}

/** Forward a received call to another destination - slow version.

 *

 * @param callid	Hash of the call to forward.

 * @param phoneid	Phone handle to use for forwarding.

 * @param data		Userspace address of the new IPC data. 

 * @param mode		Flags that specify mode of the forward operation.

 *

 * @return		Return 0 on succes, otherwise return an error code.

 *

 * This function is the slow verision of the sys_ipc_forward_fast interface.

 * It can copy all five new arguments and the new method from the userspace.

 * It naturally extends the functionality of the fast version. For system

 * methods, it additionally stores the new value of arg3 to ARG4. For non-system

 * methods, it additionally stores the new value of arg3, arg4 and arg5,

 * respectively, to ARG3, ARG4 and ARG5, respectively.

 */

unative_t sys_ipc_forward_slow(unative_t callid, unative_t phoneid,

    ipc_data_t *data, int mode)

{

	ipc_data_t newdata;

	int rc;

	rc = copy_from_uspace(&newdata.args, &data->args,

	    sizeof(newdata.args));

	if (rc != 0) 

		return (unative_t) rc;

	return sys_ipc_forward_common(callid, phoneid,

	    IPC_GET_METHOD(newdata), IPC_GET_ARG1(newdata),

	    IPC_GET_ARG2(newdata), IPC_GET_ARG3(newdata),

	    IPC_GET_ARG4(newdata), IPC_GET_ARG5(newdata), mode, true); 

}

/** Answer an IPC call - fast version.

 *

 * This function can handle only two return arguments of payload, but is faster

 * than the generic sys_ipc_answer().

 *

 * @param callid	Hash of the call to be answered.

 * @param retval	Return value of the answer.

 * @param arg1		Service-defined return value.

 * @param arg2		Service-defined return value.

 * @param arg3		Service-defined return value.

 * @param arg4		Service-defined return value.

 *

 * @return		Return 0 on success, otherwise return an error code.	

 */

unative_t sys_ipc_answer_fast(unative_t callid, unative_t retval,

    unative_t arg1, unative_t arg2, unative_t arg3, unative_t arg4)

{

	call_t *call;

	ipc_data_t saved_data;

	int saveddata = 0;

	int rc;

	/* Do not answer notification callids */

	if (callid & IPC_CALLID_NOTIFICATION)

		return 0;

	call = get_call(callid);

	if (!call)

		return ENOENT;

	if (answer_need_old(call)) {

		memcpy(&saved_data, &call->data, sizeof(call->data));

		saveddata = 1;

	}

	IPC_SET_RETVAL(call->data, retval);

	IPC_SET_ARG1(call->data, arg1);

	IPC_SET_ARG2(call->data, arg2);

	IPC_SET_ARG3(call->data, arg3);

	IPC_SET_ARG4(call->data, arg4);

	/*

	 * To achieve deterministic behavior, zero out arguments that are beyond

	 * the limits of the fast version.

	 */

	IPC_SET_ARG5(call->data, 0);

	rc = answer_preprocess(call, saveddata ? &saved_data : NULL);

	ipc_answer(&TASK->answerbox, call);

	return rc;

}

/** Answer an IPC call.

 *

 * @param callid	Hash of the call to be answered.

 * @param data		Userspace address of call data with the answer.

 *

 * @return		Return 0 on success, otherwise return an error code.

 */

unative_t sys_ipc_answer_slow(unative_t callid, ipc_data_t *data)

{

	call_t *call;

	ipc_data_t saved_data;

	int saveddata = 0;

	int rc;

	/* Do not answer notification callids */

	if (callid & IPC_CALLID_NOTIFICATION)

		return 0;

	call = get_call(callid);

	if (!call)

		return ENOENT;

	if (answer_need_old(call)) {

		memcpy(&saved_data, &call->data, sizeof(call->data));

		saveddata = 1;

	}

	rc = copy_from_uspace(&call->data.args, &data->args, 

	    sizeof(call->data.args));

	if (rc != 0)

		return rc;

	rc = answer_preprocess(call, saveddata ? &saved_data : NULL);

	ipc_answer(&TASK->answerbox, call);

	return rc;

}

/** Hang up a phone.

 *

 * @param		Phone handle of the phone to be hung up.

 *

 * @return		Return 0 on success or an error code.

 */

unative_t sys_ipc_hangup(int phoneid)

{

	phone_t *phone;

	GET_CHECK_PHONE(phone, phoneid, return ENOENT);

	if (ipc_phone_hangup(phone))

		return -1;

	return 0;

}

/** Wait for an incoming IPC call or an answer.

 *

 * @param calldata	Pointer to buffer where the call/answer data is stored.

 * @param usec 		Timeout. See waitq_sleep_timeout() for explanation.

 * @param flags		Select mode of sleep operation. See waitq_sleep_timeout()

 *			for explanation.

 *

 * @return 		Hash of the call.

 *			If IPC_CALLID_NOTIFICATION bit is set in the hash, the

 *			call is a notification. IPC_CALLID_ANSWERED denotes an

 *			answer.

 */

unative_t sys_ipc_wait_for_call(ipc_data_t *calldata, uint32_t usec, int flags)

{

	call_t *call;

restart:

#ifdef CONFIG_UDEBUG

	udebug_stoppable_begin();

#endif	

	call = ipc_wait_for_call(&TASK->answerbox, usec,

	    flags | SYNCH_FLAGS_INTERRUPTIBLE);

#ifdef CONFIG_UDEBUG

	udebug_stoppable_end();

#endif

	if (!call)

		return 0;

	if (call->flags & IPC_CALL_NOTIF) {

		ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

		/* Set in_phone_hash to the interrupt counter */

		call->data.phone = (void *) call->priv;

		STRUCT_TO_USPACE(calldata, &call->data);

		ipc_call_free(call);

		return ((unative_t) call) | IPC_CALLID_NOTIFICATION;

	}

	if (call->flags & IPC_CALL_ANSWERED) {

		process_answer(call);

		ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

		if (call->flags & IPC_CALL_DISCARD_ANSWER) {

			ipc_call_free(call);

			goto restart;

		} else {

			/*

			 * Decrement the counter of active calls only if the

			 * call is not an answer to IPC_M_PHONE_HUNGUP,

			 * which doesn't contribute to the counter.

			 */

			atomic_dec(&TASK->active_calls);

		}

		STRUCT_TO_USPACE(&calldata->args, &call->data.args);

		ipc_call_free(call);

		return ((unative_t) call) | IPC_CALLID_ANSWERED;

	}

	if (process_request(&TASK->answerbox, call))

		goto restart;

	/* Include phone address('id') of the caller in the request,

	 * copy whole call->data, not only call->data.args */

	if (STRUCT_TO_USPACE(calldata, &call->data)) {

		/*

		 * The callee will not receive this call and no one else has

		 * a chance to answer it. Reply with the EPARTY error code.

		 */

		ipc_data_t saved_data;

		int saveddata = 0;

		if (answer_need_old(call)) {

			memcpy(&saved_data, &call->data, sizeof(call->data));

			saveddata = 1;

		}

		IPC_SET_RETVAL(call->data, EPARTY);

		(void) answer_preprocess(call, saveddata ? &saved_data : NULL);

		ipc_answer(&TASK->answerbox, call);

		return 0;

	}

	return (unative_t)call;

}

/** Connect an IRQ handler to a task.

 *

 * @param inr		IRQ number.

 * @param devno		Device number.

 * @param method	Method to be associated with the notification.

 * @param ucode		Uspace pointer to the top-half pseudocode.

 *

 * @return		EPERM or a return code returned by ipc_irq_register().

 */

unative_t sys_ipc_register_irq(inr_t inr, devno_t devno, unative_t method,

    irq_code_t *ucode)

{

	if (!(cap_get(TASK) & CAP_IRQ_REG))

		return EPERM;